# US 12,761,991 B2 · Performing API services using zone-based topics within a pub/sub messaging infrastructure > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,761,991 B2 - Document ID: US12761991B2 - Status: Granted - Kind: B2 - Application number: 18/068,738 - Filed: 2022-12-20 - Published: 2024-06-20 - Granted: 2026-10-13 - Earliest claimed: 2022-12-20 - Assignees: International Business Machines Corporation - Applicants: International Business Machines Corporation - Inventors: Rong Nickle Chang; Kumar Bhaskaran - Web page: https://patentgrep.com/patent/US12761991B2 ## CPC - G06F 9/547: {Remote procedure calls [RPC]; Web services} - H04L 41/5058: {Service discovery by the service manager} - G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N) - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract A method, computer program product, and computer system for performing an Application Programming Interface (API) service using zone-based topics within a publish/subscribe (pub/sub) messaging infrastructure. An API service request sent by a client entity is received and specifies an API service to be fulfilled. A selection of an API service endpoint configured to execute the API service is received. Messages are posted to respective pub/sub zone-based topics, resulting in selection of workers subscribed to the respective zone-based topics. Each zone-based topic includes tasks to be performed in a specified one or more zones. For each zone-based topic, the tasks of the zone-based topic are implemented by executing the worker selected for the zone-based topic. The tasks of the zone-based topics include invoking the API service endpoint for the requested API service and making a fulfillment result of the API service available to the client entity. ## Claims ### Claim 1 A computer-implemented method for performing an Application Programming Interface (API) service using zone-based topics within a publish/subscribe (pub/sub) messaging infrastructure, said computer-implemented method comprising: receiving, by one or more processors, an API service request sent by a client entity, said API service request specifying the API service to be fulfilled; receiving, by the one or more processors, a selection of an API service endpoint, wherein the API service endpoint is configured to execute the API service; receiving, by the one or more processors, a selection of an API service invocation model supported by the selected API service endpoint, wherein the API service invocation model is one of a synchronous invocation model or an asynchronous invocation model, with respect to interactions between the API service endpoint and workers; posting, by the one or more processors, messages to respective pub/sub zone-based topics of a sequence of zone-based topics, based on the selected API service invocation model; selecting, by the one or more processors, the workers who are subscribed to the respective pub/sub zone-based topics, each zone-based topic of the sequence of zone-based topics comprising one or more tasks to be performed in a specified one or more zones; and implementing, by the one or more processors, for each zone-based topic of the sequence of zone-based topics, the one or more tasks, wherein said implementing of the one or more tasks is having been performed by executing a corresponding worker of the selected workers, selected for the zone-based topic, said implementing of the one or more tasks is in accordance with the selected API service invocation model, the one or more tasks of the zone-based topics include invoking the API service endpoint for the API service and making a fulfillment result of the API service available to the client entity, and the invoking of the API service endpoint is in accordance with the selected API service invocation model. ### Claim 2 (depends on 1) The computer-implemented method of claim 1, wherein for each zone-based topic of the sequence of zone-based topics, the one or more tasks include a task to update a fulfillment status indicator denoting an extent to which the API service request has been fulfilled. ### Claim 3 (depends on 1) The computer-implemented method of claim 1, wherein the API service invocation model is the synchronous invocation model. ### Claim 4 (depends on 1) The computer-implemented method of claim 1, wherein the API service invocation model is the asynchronous invocation model. ### Claim 5 (depends on 1) The computer-implemented method of claim 1, wherein the sequence of zone-based topics is denoted as T1, T2, . . . , TM, M is at least 3, said posting of a message to a first zone-based topic Tm is performed by executing a worker selected for a second zone-based topic Tm-1 (m=2, . . . , and M), the messages include the message, the workers include the worker, and the sequence of zone-based topics includes the first zone-based topic and the second zone-based topic. ### Claim 6 (depends on 5) The computer-implemented method of claim 5, wherein a worker HEAD, of the workers, receives the API service request sent by the client entity, and wherein said posting of the message to a zone-based topic T1 of the sequence of zone-based topics is performed by executing the worker HEAD. ### Claim 7 (depends on 1) The computer-implemented method of claim 1, wherein each topic of the sequence of zone-based topics is zone-based with respect to N zones, and wherein N is at least 2. ### Claim 8 (depends on 7) The computer-implemented method of claim 7, wherein N is constant over the sequence of zone-based topics. ### Claim 9 (depends on 7) The computer-implemented method of claim 7, wherein N is not constant over the sequence of zone-based topics and differs for at least two of the sequence of zone-based topics. ### Claim 10 (depends on 7) The computer-implemented method of claim 7, further comprising: in response to a zone related problem pertaining to executing of a first worker selected for a zone-based topic of the sequence of zone-based topics wherein the first worker is executed in a first zone of the N zones, replacing, by the one or more processors, the first worker by a second worker subscribed to the zone-based topic and is executed in a second zone of the N zones. ### Claim 11 (depends on 1) The computer-implemented method of claim 1, wherein the fulfillment result of the API service is asynchronous to the client entity. ### Claim 12 (depends on 1) The computer-implemented method of claim 1, wherein the one or more processors are general purpose processors. ### Claim 13 (depends on 1) The computer-implemented method of claim 1, wherein the one or more processors comprise an application specific integrated circuit (ASIC), and wherein electrical circuitry within the ASIC is hard wired to perform the computer-implemented method. ### Claim 14 A computer program product, comprising: one or more computer readable hardware storage devices having computer readable program code stored therein, said program code containing instructions executable by one or more processors of a computer system to implement a method for performing an Application Programming Interface (API) service using zone-based topics within a publish/subscribe (pub/sub) messaging infrastructure, said method comprising: receiving, by the one or more processors, an API service request sent by a client entity, said API service request specifying the API service to be fulfilled; receiving, by the one or more processors, a selection of an API service endpoint, wherein the API service endpoint is configured to execute the API service; receiving, by the one or more processors, a selection of an API service invocation model supported by the selected API service endpoint, wherein the API service invocation model is one of a synchronous invocation model or an asynchronous invocation model, with respect to interactions between the API service endpoint and workers; posting, by the one or more processors, messages to respective pub/sub zone-based topics of a sequence of zone-based topics, based on the selected API service invocation model; selecting, by the one or more processors, the workers who are subscribed to the respective pub/sub zone-based topics, each zone-based topic of the sequence of zone-based topics comprising one or more tasks to be performed in a specified one or more zones; and implementing, by the one or more processors, for each zone-based topic of the sequence of zone-based topics, the one or more tasks, wherein said implementing of the one or more tasks is performed by executing a corresponding worker of the selected workers, selected for the zone-based topic, said implementing of the one or more tasks is in accordance with the selected API service invocation model, one or more tasks of the zone-based topics include invoking the API service endpoint for the API service and making a fulfillment result of the API service available to the client entity, and the invoking of the API service endpoint is in accordance with the selected API service invocation model. ### Claim 15 (depends on 14) The computer program product of claim 14, wherein for each zone-based topic of the sequence of zone-based topics, the one or more tasks include a task to update a fulfillment status indicator denoting an extent to which the API service request has been fulfilled. ### Claim 16 A computer system, comprising: one or more processors; one or more memories; and one or more computer readable hardware storage devices, said one or more computer readable hardware storage devices containing program code executable by the one or more processors via the one or more memories to implement a method for performing an Application Programming Interface (API) service using zone-based topics within a publish/subscribe (pub/sub) messaging infrastructure, said method comprising: receiving, by the one or more processors, an API service request sent by a client entity, said API service request specifying the API service to be fulfilled; receiving, by the one or more processors, a selection of an API service endpoint, wherein the API service endpoint is configured to execute the API service; receiving, by the one or more processors, a selection of an API service invocation model supported by the selected API service endpoint, wherein the API service invocation model is one of a synchronous invocation model or an asynchronous invocation model, with respect to interactions between the API service endpoint and workers; posting, by the one or more processors, messages to respective pub/sub zone-based topics of a sequence of zone-based topics, based on the selected API service invocation model; selecting, by the one or more processors, the workers who are subscribed to the respective pub/sub zone-based topics, each zone-based topic of the sequence of zone-based topics comprising one or more tasks to be performed in a specified one or more zones; and implementing, by the one or more processors, for each zone-based topic of the sequence of zone-based topics, the one or more tasks, wherein said implementing of the one or more tasks is performed by executing a corresponding worker of the selected workers, selected for the zone-based topic, said implementing of the one or more tasks is in accordance with the selected API service invocation model, the one or more tasks of the zone-based topics include invoking the API service endpoint for the API service and making a fulfillment result of the API service available to the client entity, and the invoking of the API service endpoint is in accordance with the selected API service invocation model. ### Claim 17 (depends on 16) The computer system of claim 16, wherein for each zone-based topic of the sequence of zone-based topics, the one or more tasks include a task to update a fulfillment status indicator denoting an extent to which the API service request has been fulfilled.